1. Field
This invention relates to pharmaceutical compositions generally, and to stabilized gonadotropin containing preparations specifically.
2. State of the Art
Relatively pure gonadotropin preparations are commercially available. For example, compositions containing naturally derived human menopausal gonadotropin ("HMG") and naturally derived human chorionic gonadotropin ("HCG") are available as freeze-dried preparations under the trade designations "Humegon" and "Pregnyl," respectively, from Organon International, bv of Oss, NL. Pregnant mare gonadotropin is also available in a freeze dried form from the same company.
A bulking agent, e.g. mannitol, is added to these preparations before lyophilization. They do not require the addition of a stabilizer to ensure an adequate shelf-life. Evidently whatever natural contaminants remain after the purification process act to stabilize the preparations in freeze-dried form.
Recently however, with the advent of more effective production and purification techniques, preparations of certain very pure gonadotropins are insufficiently stable. They degrade in a relatively short time, losing activity. In order to prevent or slow down this degradation, attempts were made to freeze-dry (lyophilize) the preparations. Lyophilization has only been partially successful however.
A need exists for a gonadotropin containing pharmaceutical preparation which is stable over a sufficiently long period of time for the product to be manufactured, shipped, and stored prior to use. The need is especially great for a stable preparation containing more than one gonadotropin.